Contrast Media in Cardiovascular System
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Questions and Answers

What is the primary central effect on the heart when a contrast media is injected?

  • Cardiac output
  • Myocardial contractility (correct)
  • Electrophysiology
  • Coronary blood flow

    • What is the primary effect on the peripheral vasculature when a large bolus of contrast media is delivered?

  • Generalized vasodilatation (correct)
  • Increased blood pressure
  • cardiac arrhythmia
  • Vasoconstriction

    • What is the effect of contrast media on plasma volume?

  • It decreases plasma volume
  • It has no effect on plasma volume
  • It expands plasma volume (correct)
  • It has a variable effect on plasma volume

    • What is the effect of contrast media on blood coagulation?

    <p>It has anti-coagulant properties</p> Signup and view all the answers

    What is the effect of high osmolality contrast media on smooth muscles?

    <p>It causes vasodilatation</p> Signup and view all the answers

    Why does contrast media injection into the coronary arteries have a marked depressant effect on cardiac pump function?

    <p>Due to the combination of direct and indirect neurally mediated effects</p> Signup and view all the answers

    What is the effect of contrast media on coronary blood flow?

    <p>It increases coronary blood flow by a steal phenomenon</p> Signup and view all the answers

    Why are highly concentrated contrast media used to visualize small cardiac vessels?

    <p>Because they have high iodine concentration</p> Signup and view all the answers

    What happens to cardiac contractility initially after the injection of ionic contrast media?

    <p>It decreases</p> Signup and view all the answers

    What happens to the calcium to sodium ratio after the injection of ionic contrast media?

    <p>It may not change</p> Signup and view all the answers

    Why does cardiac contractility decrease after the injection of ionic contrast media?

    <p>Due to the binding of calcium ions to the anionic compound</p> Signup and view all the answers

    What happens to the extracellular fluid after the injection of contrast media with higher osmolality than plasma?

    <p>It moves from the extravascular space into the capillaries</p> Signup and view all the answers

    What is the effect of cellular dehydration on cardiac contractility?

    <p>It increases contractility</p> Signup and view all the answers

    Why does nonionic contrast media not cause depressed cardiac contractility?

    <p>Because it does not bind to calcium ions</p> Signup and view all the answers

    What is the effect of nonionic contrast media on cardiac contractility?

    <p>It increases contractility</p> Signup and view all the answers

    What is the effect of contrast media injection on hydrogen concentration?

    <p>It increases hydrogen concentration</p> Signup and view all the answers

    What is the effect of hyperosmolar contrast solution on cardiac vessels?

    <p>Vasodilatation</p> Signup and view all the answers

    What is the result of injecting CM into a coronary artery?

    <p>All of the above</p> Signup and view all the answers

    What is the effect of hypertonic CM on the heart?

    <p>Bradycardia</p> Signup and view all the answers

    What is the effect of CM on vascular endothelium?

    <p>Irritation or damage</p> Signup and view all the answers

    What is the clinical symptom of endothelial damage?

    <p>Sensation of heat and pain</p> Signup and view all the answers

    What increases the incidence of post-phlebographic thrombosis?

    <p>Increasing chemotoxicity</p> Signup and view all the answers

    Why is thrombosis seen less in arm veins than leg veins?

    <p>Higher fibrinolytic activity in arm veins</p> Signup and view all the answers

    What can reduce the incidence of post-phlebographic thrombosis?

    <p>Using low osmolality CM</p> Signup and view all the answers

    What happens to the cells when exposed to high osmolality Contrast Media?

    <p>They shrink and pull apart</p> Signup and view all the answers

    What is the effect of ionic Contrast Media on cardiac contractility?

    <p>It initially decreases and then increases contractility</p> Signup and view all the answers

    What is the effect of Contrast Media on coronary perfusion?

    <p>It increases perfusion</p> Signup and view all the answers

    What is the effect of Contrast Media on conduction in the heart?

    <p>It slows conduction</p> Signup and view all the answers

    What is the effect of Contrast Media on peripheral vessels?

    <p>It causes vasodilatation and decreased blood pressure</p> Signup and view all the answers

    Why is it important to hydrate patients before Contrast Media administration?

    <p>To reduce the risk of nephrotoxicity</p> Signup and view all the answers

    What is the effect of Contrast Media on red blood cells?

    <p>They become dehydrated and deformed</p> Signup and view all the answers

    Why is it recommended to hydrate patients with up to 2L of normal saline before Contrast Media administration?

    <p>To reduce the osmotic activity of Contrast Media</p> Signup and view all the answers

    Why should administration of contrast media during pregnancy be limited?

    <p>Because it should only be performed for essential indications</p> Signup and view all the answers

    What percentage of contrast media is excreted by the kidneys in the first hour?

    <p>30%</p> Signup and view all the answers

    Why can water-soluble contrast media pass through the glomerular pores?

    <p>Because they are small in size and not bound to protein</p> Signup and view all the answers

    What is the percentage of contrast media excreted by the kidneys in the next 6 hours?

    <p>70-75%</p> Signup and view all the answers

    What happens to contrast media excretion in patients with impaired kidney function?

    <p>Extrarenal excretion is more pronounced</p> Signup and view all the answers

    What is the recommendation for breastfeeding after contrast media administration?

    <p>Breast milk should not be fed to the infant for 3 days</p> Signup and view all the answers

    Study Notes

    Contrast Media Cardiovascular System

    • Primary central effects on the heart:

    • Myocardial contractility

    • Electrophysiology

    • Coronary blood flow

    • Primary effects on the peripheral vasculature:

    • Vasodilatation

    • Hypotension

    • Tachycardia

    • Contrast Media (CM) expands plasma volume and has anti-coagulant properties

    • CM causes generalized vasodilatation, resulting in hypotension and tachycardia, mainly due to hyperosmolality mediated effect on smooth muscles

    • Effects on the heart are greatest when injected directly into the coronary arteries

    • Marked depressant effects on cardiac pump function, which are dose-dependent and cumulative

    Electrophysiology of the Heart

    • CM injection into a coronary artery may result in disturbances of electrophysiology, leading to ECG changes
    • Effects depend on CM osmolality and changes in cation concentrations
    • Lower osmolality results in fewer changes, and nonionic CM has fewer changes
    • Tachycardia, bradycardia, asystole, and other arrhythmias can occur
    • Injection of hypertonic CM results in slowing of electrophysiology, leading to bradycardia

    CM and Blood Vessel Walls

    • CM can act on vessel walls and contents, causing irritation or damage

    • Clinical symptoms include sensation of heat and pain, and initiation of thrombus formation

    • Endothelial damage increases with:

      • Increasing chemotoxicity
      • Increasing osmolality
      • Increasing contact time between endothelium and CM

    • Consequences of endothelial damage:

      • Thrombosis is more likely
      • Large molecules can pass through the endothelium, causing problems

    Summary of CM Effects on the Cardiovascular System

    • Cardiac contractility:
      • Ionic CM: contractility decreases then increases
      • Nonionic CM: contractility only increases
    • Coronary perfusion: increases, but may lead to a steal effect
    • Conduction: delayed
    • Heart rhythm: all types of arrhythmias are possible
    • Peripheral vessels:
      • Pain and heat caused by hyperosmolality of CM
      • Vasodilatation causes decreased blood pressure
    • Endothelium:
      • Affected by hyperosmolality and chemotoxicity of CM
      • Cells become dehydrated, shrink, and junctions become leakier
    • Red blood cells:
      • Become dehydrated and deformed
      • Cannot pass through capillaries easily, increasing resistance and workload on the heart
    • Capillaries:
      • Endothelium becomes leaky as cells shrink and junctions open
    • Coagulation:
      • CM inhibits coagulation, more pronounced in ionic CM

    Contrast Media and Dehydration

    • All CM are osmotically active substances that absorb water from their environment
    • Patients should be adequately hydrated with up to 2L of normal saline before CM administration
    • Electrolyte loss must be compensated for previously
    • Dehydration increases the risk of nephrotoxicity

    Clearance of Contrast Media

    • Kidney: water-soluble CM is excreted by glomerular filtration
    • Small size of CM molecules allows passage through glomerular pores
    • CM molecules are not bound to protein (albumin)
    • About 30% of CM is excreted by kidneys in the first hour, and 70-75% in the next 6 hours
    • Other routes of excretion (less than 5%): sweat, tears, saliva, bile, and pancreas
    • In patients with impaired kidney function, extrarenal CM excretion is more pronounced, and there is increased protein binding for these substances

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    Description

    This quiz covers the effects of contrast media on the heart and peripheral vasculature, including changes in myocardial contractility, coronary blood flow, and blood pressure.

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